As is well known, the heart has four chambers for receiving and pumping blood to various parts of the body. During normal operation of the heart, oxygen-poor blood returning from the body enters the right atrium. The right atrium fills with blood and eventually contracts to expel the blood through the tricuspid valve to the right ventricle. Contraction of the right ventricle ejects the blood in a pulse-like manner into the pulmonary artery and each lung. The oxygenated blood leaves the lungs through the pulmonary veins and fills the left atrium. The left atrium fills with blood and eventually contracts to expel the blood through the mitral valve to the left ventricle. Contraction of the left ventricle forces blood through the aorta to eventually deliver the oxygenated blood to the rest of the body.
There are conditions in which the heart valves (i.e., mitral valve, aortic valve, pulmonic value and tricuspid valve) do not close completely (i.e., incompetence) causing reverse flow of blood through the valve (i.e., regurgitation) resulting in a murmur as blood goes back through the valve. Often times, the valve leaflets are found to have been damaged by infection (e.g., streptococcus). The valve leaflets damaged by infection are typically thickened, especially on the edges, therefore incapable of sealing the opening across which they lie.
Other times, the valve leaflets are found to be atherosclerotic (i.e., thickened and calcified). Typical treatments for atherosclerosis include inflating a balloon in the valve to break plaque loose from the valve and, for severe cases, valve replacement with either a mechanical or pig valve. There are some conditions in which the valve leaflets show indication of subacute bacterial endocarditis. Typically, a valve replacement procedure is conducted to treat subacute bacterial endocarditis.
Collagen-containing tissue is ubiquitous in the human body and demonstrates several unique characteristics not found in other tissues. Intermolecular cross links provide collagen-containing tissue with unique physical properties of high tensile strength and substantial elasticity. A property of collagen is that its material properties can be changed when elevated in temperature and force is applied. The molecular response to temperature elevation and force is believed to be the result of rupture of the collagen stabilizing cross links or the result of a change in the hydration of the tissue.
There has been discussion in the existing literature regarding alteration of collagen-containing tissue in different parts of the body. One known technique for effective use of this knowledge of the properties of collagen is through the use of infrared laser energy to effect tissue heating. The use of infrared laser energy as a corneal collagen shrinking tool of the eye has been described and relates to laser keratoplasty, as set forth in U.S. Pat. No. 4,976,709. The importance of controlling the localization, timing and intensity of laser energy delivery is recognized as paramount in providing the desired soft tissue shrinkage affects without creating excessive damage to the surrounding non-target tissues. Another known technique of altering collagen is described in U.S. Pat. No. 5,458,596 to treat joints. U.S. Pat. No. 5,437,664 describes using a catheter for venous occlusion and coagulation of blood.